Refrigerating method and apparatus utilizing dry ice



Ian. M, 1950 A 2,496,241

G. B. W GNER V REFRIGERATING METHOD AND APPARATUS UTILIZING DRY ICEFiled Jan; 19, 1946 til 4:. at i application January I9, 19%, derial No.dd2,3l2

(Cl. 62-illi.5)

3 Illa.

This invention relates to novel refrigerating method and apparatus orthe nature disclosed in my eopending application Ser. No. 66 L700, filedJuly into, new Patent l lo. ihtdilhlll, granted November to, race. Inthat application I have disclosed a storage chamber refrigerated hyevaporation gas from Dry Ice conducted from a Dry Ice box througharefrigerant pipe in the chamher. The temperature oi the chamber iscontrolled by venting the pipe at predetermined pressure. Normalevaporation of the Dry Ice is ordinarily sumcient to maintain desiredtemperatures within the chamber but emergencies may arise that willrequire an extra surge of evaporation to maintain a desiredpredetermined temperature. The primary object of my invention hereinresides in the production of novel method and apparatus forautomatically providing and main... taining such additional evaporationand refrigeration whenever occasion demands.

The invention contemplates the employment of means in the nature of acompressor associated with the refrigerant pipe for creating a suctionand increasing the evaporation of the Dry Ice when the temperature inthe chamber reaches a predetermined maximum, a thermostat in the beingassociated with the compressor for automatically effecting the suctionwhen required. The production or a novel method and apparatus of thisnature comprises a further object of the invention.

The compressor can be driven by any suitable motor under control of thethermostat and I have herein, by way of example, illustrated anddescribed the employment of an electric motor and a gas pressure motorfor this purpose. In the latter case, a second Dry Ice box is employedto provide evaporation gas for operating the motor and the thermostat isassociated with and adapted automatically, when the temperature in thechamber reaches a predetermined maximum, to open a, valve and permit theflow of gas from the box to the motor, whereby causing the motor tooperate the compressor and create the aforesaid suction.

These and other features of the invention will be best understood andappreciated from the following description of preferred embodimentsthereof selected for purposes of illustration and shown in theaccompanying drawing in which Fig. 1 is a fragmentary sectional viewthrough an apparatus embodying my invention and employing an electricmotor,

Fig. 2 is a like apparatus employing a gas pressure motor.

lid

d Referring first to Fig. l of the drawing, it indicates a double walledcontainer insulated loctween the walls and it indicates a cover ior'thecontainer. The interior chamber it of the contamer provides storagespace for perishable products.

Centrally disposed within and spaced from the walls of the cover is asheet aluminum Dry Ice box it. The box is supported directly on thebottom walllt of the cover by means or an aluminum collar it in metal tometal contact with the box and the bottom wall of the cover. The box isopen at one end and can be anchored at its corners to the cover walls inthe manner disclosed in my said copending application. The open end ofthe box is adapted to be closed by a removable closure includinginsulation it permitting the refilling of the box with Dry Ice it. Arefrigerating pipe it extending from the box it outwardly i through thewall it is formed into a coil within the storage chamber it and ventsoutwardly through the cover at it. an adjustable pressure relief valveit is provided in the pipe lit and is adapted to permit the escape ofgas from the pipe at predetermined pressure. A temperature of 110 F. isnormally maintained in the box it and the temperature to be maintainedinv the storage chamber depends on the product contained.

The box it is heavily insulated except for the metal to metal contactthrough the supporting collar it and the evaporation of the ice will bein proportion to the heat acqulredfrom the chambet it plus heat passingthrough the insulation. Ihave discovered that an insulated storagechamber can be refrigerated and a predetermined temperature maintainedby evaporating Dry Ice within a closed chamber and conducting theevaporation gas therefrom through a pipe in the storage chamber at apredetermined pressure controlled at the vent end of the pipe, and Ihave employed this principle in the apparatus disclosed herein and in mysaid copending appllcation. The relief valve 28 is set to permit theescape of gas at a pressure which has been predetermined to produce andmaintain the required low temperature in the storage chamber. It will beapparent that evaporation will be greater when relatively small pressureis required for escape of the gas and that the evaporating action willoperate to lower the temperature in proportion to the evaporation. Ihave employed this apparatus in the storage of perishable products andhave maintained a predetermined temperature of 45 F. uniformly withinless than 2 over a. period of 104 hours. The device is particularlyadapted to the preserving of whole blood, blood plasma and likeperishable products and to the shipping of such products in containersembodying the invention.

The invention is applicable to wide and varied use in the storing andthe combined storing and transporting of perishable products.Furthermore while it is particularly adapted to use-in portablecontainers it is equally adaptable to fixed storage refrigeration, largerefrigeration truck units, etc. Such units are employed to transportfruit and other perishable products relatively long distances andthrough climates of varying temperatures, and when large shipments arebeing transported it may occasionally be necessary to provide additionalrefrigeration to maintain the chamber and products below a predeterminedmaximum temperature. My invention herein disclosed is particularlyadapted to provide this additional refrigeration Mounted on the cover I2is a compressor 30 as-' sociated with an electric motor 32. The pipe 2'is connected to the intake port of the compressor which has an exit portat 34. The motor is under the control of a thermostat 36 mounted on thecover wall It within the chamber l4 and con-. nected to the motor bywiring 38. The thermostat is set to cause the motor to operate at apredetermined maximum temperature which is to be maintained within thechamber ll.

Normally, the evaporation of the Dry Ice under control of the valve 28is suilicient to maintain the required low temperature within thechamber but such factors as excessive extraction of heat from the storedproducts or passage of the load through an unduly warm atmosphere maytemporarily cause the temperature in the storage chamber to rise to thepredetermined maximum. In such case the thermostat automaticall operatesto switch on the motor and drive the compressor which in turn reducesthe gas pressure in the pipe 24 and increases the evaporation of the DryIce 22. Such increased surge of evaporation lowers the temperature inthe storage chamber to a point below the predetermined maximum andserves in conjunction with the pressure control at 28 continuously tomaintain the required range of temperature in the storage chamber evenin extreme emergencies. It will be apparent that such maintenance isextremely important since the increased temperature of the chamber mightotherwise deleteriously affect and cause loss of the perishableproducts.

In Fig. 2 of the drawing I have illustrated a similar refrigeratingapparatus employing a gas pressure motor to drive the compressor. Theparts of this apparatus which correspond to those illustrated in Fig. 1are indicated by like reference characters primed and include acontainer it provided with a cover I! and having a storage chamber M.The cover has a bottom wall l6 and a Dry Ice box I! is supported on thiswall by means oi. an aluminum collar it. A pipe 24' from the box Iprovides a refrigerating coil in the storage chamber, extends outwardlyof the cover at 26 and is ventedby a relief valve 28'.

Mounted on the cover I! is a compressor II and a gas pressure motor 42having pistons connected by a piston rod M as specifically described inmy said copending application. The pipe 2G is connected to the intakeport of the compressor which has an exit port at It. The motor 42 isoperated by evaporation gas from Dry Ice 48 withm a second box so, thisbox being mounted am 4 iacent to but insulated from the box ii. A pipe52 extends from the box ill to the intake port of the motor which has anexit port II. A valve It in the pipe 52 is under the control of athermostat It secured to the bottom cover wall It. The thermostat isconnected by wiring II to a solenoid associated with the valve 58 andadapted automatically to open the valve when the temperature in chamberI4 reaches said predetermined maximum.

As in the apparatus of Ffig. l, evaporation of Dry Ice 22' under controlof the valve 28' is normally sufllcient to maintain the required lowtemperature within the storage chamber. However, if and when'thetemperature within the chamber rises to said predetermined maximum, thethermostat automatically operates to open the valve 58 and permit gasunder pressure to flow from the box 50 to and drive the motor 42. Themotor in turn drives the compressor, reduces the gas pressure inthe pipe24' and increases the evaporation of the Dry Ice 22', whereby loweringthe tempera,- ture in the storage chamber in the manner heretoioredescribed in. connection with Fig. 1.

Having now disclosed my invention what I claim as new' and desire tosecure by Letters Patent is:

l. A method oi maintaining an insulated storage zone at predeterminedtemperature, which consists in evaporating Dry Ice within a closed zone,conducting the evaporation gas therefrom along a closed path disposed inheat exchanging relation to the storage zone, controlling thetemperature of the storage zone by venting the closed path atpredetermined pressure, evaporating Dry Ice within a second closed zone,and utilizing the evaporation gas from the second closed zone to drive acompressor and create a suction from the first closed zone through saidpath when the temperature in the storage zone reaches a predeterminedmaximum.

2. A refrigerating apparatus comprising a container having a storagechamber within insulated walls, a closed Dry Ice containing boxassociated with the chamber, a refrigerant pipe from the box having anintermediate portion disposed within the chamber and an outer portiondisposed outside of the chamber, a valve for controlling the vent of gasfrom the pipe exteriorly of the chamber, a compressor associated withthe outer portion of the pipe outwardly of the valve for creating asuction from the box through the pipe, means including a thermostat inthe chamber for automatically controlling the operation of thecompressor, a second closed Dry Ice containing box, and means includinga motor under control of the thermostat and arranged to utilize theevaporation gas from the second box to drive the compressor and create asuction from the first named box through the pipe when the temperaturein the chamber reaches a predetermined maximum.

3. Arefrigerating apparatus comprising a container having a storagechamber within insulated walls, a closed Dry Ice containing boxassociated with the chamber, a refrigerant pipe from the box having anintermediate portion disposed within the chamber and an outer portiondisposed outside of the chamber, a valve for controlling the vent of gasfrom the pipe exteriorly of the chamber, a compressor associated withthe outer portion of the pipe outwardly of the valve for creating asuction from the box through the pipe, means including a thermostat inthe chamber for automatically controlling the operation of thecompressor, a motor associated with the com- Dressor, a second closedDry Ice containing box,

REFERENCES CITED The following references are of record in the file ofthis patent:

6 UNITED STATES PATENTS Number Name Dcte Comer Dec. 19, 1933 SherrickMar. 20, 1934 Lewis Feb. 23, 193'? Scott Nov. 1.8, 1941 McMechan July31, 1945 Isenberg et a1 Aug. 28, 1945 Newton Mar. 9, 1948

